Woodlands as quality breeding habitat for black-capped vireos

Authors: T. L. Pope, M. L. Morrison, and R. N. Wilkins

Identifying vegetation types that result in the highest quality habitat will help direct management and conservation activities designed to recover endangered species. Shrubland is considered to result in high quality habitat for black-capped vireos (Vireo atricapilla), whereas deciduous and oak-juniper woodlands are considered to result in marginal habitat (i.e., lower quality). We investigated differences in nest and fledgling survival among shrubland and woodland vegetation types. We monitored 302 black-capped vireo nests in 259 territories from 2008 to 2010 in Kerr County, Texas and collected vegetation data at each nest. We also resighted 350 fledglings to estimate individual survival. Nest survival and fecundity did not differ statistically among vegetation types. Although nest-site characteristics differed among vegetation types, none affected nest survival. Nests that were parasitized were less likely to survive and parasitism was the only variable to affect survival of those measured. Parasitism frequency was nearly twice as great in shrubland (22%) than in either woodland type (12% in each) and varied by year (31% in 2008 to 0% in 2010). Vegetation type and proximity of the nest to oak-juniper woodland did not affect fledgling survival. Our results suggest woodlands may result in good quality habitat in areas with large populations of black-capped vireos. Recognizing woodlands as non-typical, yet good quality, habitat will allow managers to incorporate these vegetation types into management plans and make recommendations for  conservation incentive programs directed at private landowners.

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